book = ["yuwen", "shuxue", "english"]
print(book)
print(book[0])
print(book[-1])

# append
book.append("bal")
print(book)

# del
del book[0]
print(book)

# sort
book.sort()
print(book)

# 反转列表元素的排列顺序
book.reverse()
print(book)

# length
print(len(book))
